The problem is that there's only one color scheme for all the boxes in a given box plot:

The goal is to end up with a view like this, where the boxes are colored like the underlying marks:

Can you build a single-worksheet view that duplicates the above?

A starter workbook is attached. I'll add the solution I came up with on or after Monday, 27 April, though if you want to peek you can see what I came up with in the link above. Please add a comment below (without spoilers, please) with how difficult you found this, ranking from 1 (easy) to 5 (extremely difficult or impossible).

A solution:

Use dual-axes. Tableau only lets us have a single box plot reference line for each axis (the axis being generated by a continuous pill on Rows or Columns) with a single color scheme for that box plot, so to get multiple different colors for the box plots we use multiple axes and then join them in a multiple axis. In order to prevent values being duplicated on each axis, I created a measure for each box plot using a record level calc like SUM(IF [Department] == "Furniture" THEN SUM([Sales]) END) and used those in a dual-axis chart:

The box plot colors were created using Tableau's box plot colors:

And then I chose a color palette for the marks to reflect the available box plot colors.

Alternative Solutions

There are at least a few of other potential solutions to this:

1) Create a worksheet for each distinct discrete value then put them all in a dashboard, turning off Show Headers for the Y axis for all but the left-most worksheet.

2) Build 5 calculations for each distinct discrete value (whisker ends, 25/50/75th %iles) that only return non-Null values for that discrete, then put them all on the LOD and build reference bands & lines using the BYO pre-8.0 box plot technique.

3) Add 20 records to the data source for each distinct discrete value and then use those marks to draw the box plots as polygons on a dual axis. Given some work in the data source to automatically add those records and a ton of calculations, this is the only solution that I can think of that would be able to draw an arbitrary number of individually colored box plots.

I think I've come up with a solution that works to do distinct colors for any number of box plots.

1) Add the regular grey box plots from the reference lines

2) Create the following calculations to find your Upper and Lower Quartiles

Upper Quartile: WINDOW_PERCENTILE(SUM([Sales]), .75)

Lower Quartile: WINDOW_PERCENTILE(SUM([Sales]), .25)

3) Create a third calculation, Distance Between Quartiles

[Upper Quartile]-[Lower Quartile]

4) Bring the Lower Quartile calculation onto the Rows Shelf. Set Mark type to Gantt Bar. Set the secondary axis to

using Dual-Axis, and synchronize the axes. Now you should have a Gantt bar at the same place at the lower quartile mark of the box plot. You may need to adjust the Table Calc runs for it to calculate correctly

5) Bring the Distance Between Quartiles calculation onto the Size of the Gantt marks card. This should make the Gantt bar go the full length of the box. Expand the size so it matches the width exactly.

6) Finally bring whatever is on the Columns shelf onto the Color of the Gantt marks. Now each box plot is colored distinctly.

I have a comparison whisker plot for two different groups on a dashboard and I have a dynamic median line belonging to each of the groups going over them ( Created by using dual axis). Can you please let me know on how to color the boxes without using a dual axis, I saw your solution and it doesn't seem to work on mine.